This invention pertains to the field of shredders. More specifically, the invention relates to an articulated top blocker for a paper shredder.
In order to destroy documents to preserve their confidentiality, shredders exist which cut the paper into narrow strips or chips. Typically, the cutting is achieved by a pair of cutting cylinders having a series of circular cutters arranged along the axis of a shaft. The cutters of one shaft are offset so that they pass between the cutters of the other shaft. In addition, the cutters may be either a straight-cut type, which produces narrow strips of paper, or a cross-cut type, which produces small paper chips.
During operation of a paper shredder, paper particles may begin to collect inside the shredder housing, especially in the area behind the cutting cylinders, eventually causing the shredder to lock up or jam. These potentially damaging particles have two common sources: (1) cut paper particles can be swept inside the shredder housing by the normal forward motion of the cutters; and (2) uncut or partially cut paper particles can be dragged inside the shredder housing when the motion of the cutters is reversed. Unless the paper particles trapped inside the shredder are allowed to escape, the shredder will continue to lock up or jam and not function properly.
One typical solution to this problem is to provide auxiliary strippers or blockers on top of the cutting shafts between adjacent cutters. Examples of paper shredders that use such strippers are disclosed in U.S. Pat. Nos. 5,375,782 and 5,474,243, both to Schwelling. In each of these references, Schwelling discloses a paper shredder having a pair of cutting rollers, a plurality of cutting disks arranged on each cutting roller, a plurality of strippers below or on the side of each cutting roller, and a plurality of auxiliary strippers on the top of each cutting roller between adjacent cutting disks. Both the strippers and the auxiliary strippers, however, are fixed in position by a pair of spaced-apart parallel rods. As a result, the strippers and the auxiliary strippers disclosed by Schwelling serve to trap paper particles that find their way into the shredder housing and behind the cutting disks.
Accordingly, it is an object of the present invention to provide a solution to the problem of paper particles collecting inside a shredder that allows trapped paper particles to escape during normal operation of the shredder in the forward direction, but also blocks the entry of paper particles during operation of the shredder in the reverse direction. In the present invention, a shredder is provided comprising a pair of cutting cylinders with cutting shafts and spaced-apart cutter disks mounted on the cutting shafts, and an articulated top blocker rotatably mounted above the center axis of each cutting shaft. The articulated top blocker has a base and at least one stripper extending outward from the base toward the cutting shaft between adjacent cutter disks.
As a result of the articulated top blocker's ability to rotate, the articulated top blocker allows paper particles trapped in the paper shredder to be evacuated during normal operation in the forward direction, while preventing accumulation of paper particles in the shredder during operation in the reverse direction. Consequently, the shredder of the present invention is an improvement over prior art shredders that prevents paper particles from collecting inside a shredder causing the shredder to lock up or jam.